Testing method for components with reception capabilities

ABSTRACT

A method for comparing the quality of components with signal reception capabilities. The method generally includes the steps of: (1) providing at least two test vehicles, each equipped with a component to be tested, (2) providing each vehicle with a device for recording the output of the component to be tested, (3) providing at least one of the two vehicles with a video recording device, (4) simultaneously traveling a test route with the two vehicles remaining in close proximity, (5) recording the output signals of the two components to be tested as the vehicles travel the test route, (6) providing a video recording of the vehicles traveling the test route and (7) comparing the recorded signals of the two components while taking into consideration environmental conditions shown in the video recording. The present invention also provides a method for automatically rating the sound quality of a recorded FM broadcast. The method generally includes the steps of (1) computing the average signal level at a frequency above the normal FM modulation frequency, (2) computing the average signal level of the FM pilot signal and (3) subtracting the average signal level computed in step (1) from the average signal level of the FM pilot signal.

BACKGROUND OF THE INVENTION

The present invention relates to testing methods and more particularlyto methods for testing components having broadcast signal receptioncapabilities.

Because of consumer demand, the automotive industry has placed highemphasis on providing vehicles with high quality audio and receptionsystems. This is true not only in high end vehicles, but also in mid- tolow-end vehicles. To achieve high quality sound when playing AM and FMbroadcasts, it is imperative that the audio system include a highperformance reception system. Without high quality signal reception,even the most advanced audio systems are incapable of providing thedesired sound quality when playing AM and FM broadcasts.

Conventionally, vehicle audio systems, and particularly receptionsystems for vehicle audio systems, are tested or evaluated by assemblinga team of individuals (“raters”) who ride in the vehicle and listen tothe audio system as the vehicle travels a predetermined test route. Theroute is selected to travel through selected geographical areas wheredefects in the broadcast signal are likely to occur. For example, theroute is selected to pass through areas where such defects as intrusion,overload, multipath and adjacent channel interference are likely tooccur. By listening to the audio system throughout the test route,raters are capable of determining when various problems are present inthe broadcast signal. Based on this analysis, the raters are able toprovide a subjective opinion of the quality of sound produced by theaudio system. To compare the quality of two different systems, theraters may travel the same route in a separate vehicle with a secondsystem, and make comparisons between the sound and reception qualityproduced by the two systems.

This conventional method of testing and evaluation suffers from numerousdeficiencies related to the availability and quality of raters, thecomparative value of data used as the basis for assessment, and theprecise timing and location of the test.

First, it is difficult to coordinate and assemble a team of raters toparticipate in extensive test activities, and it is even more difficultfor that team to provide a high degree of experience and consistency injudgment.

Second, it is difficult for a team of raters to form a comparativeassessment of alternative audio and reception systems based on the samedata and using objective standards, since the assessment is necessarilyinstantaneous and judgmental.

Third, it is impossible to form an opinion of sound and receptionquality, which is not affected by background noise such as might becaused by traffic, road conditions, weather and even conversation in thevehicle.

Finally, it is impossible for one rater to compare the quality ofalternative audio or reception systems under identical broadcastconditions. The relative capabilities of such systems to provide qualityoutput can only be accurately assessed at the precise moment ofbroadcast since that quality is significantly affected by broadcastcontent (e.g. classical music, rock music or voice), frequencymodulation, weather conditions (e.g. cloudy or sunny), direction (egnorth, south etc.) and location (e.g. under an overpass, through atunnel, next to a tall building, near to power lines etc.).

SUMMARY OF THE INVENTION

The aforementioned problems are overcome by the present inventionwherein a testing method is provided that permits direct comparison ofaudio and reception systems, and components thereof, such as antennas orradio receivers. The method generally includes the steps of: (1)providing at least two test vehicles, each equipped with a component tobe tested, (2) providing each vehicle with a device for recording theoutput of the component to be tested, (3) providing at least one of thetwo vehicles with a video recording device, (4) simultaneously travelinga test route with both the vehicles remaining in close proximity, (5)recording the output signals of the components being tested as thevehicles travel the test route, (6) providing a video recording of thevehicles traveling the test route, (7) playing back at least portions ofthe recorded output while simultaneously playing back the correspondingportions of the recorded video, and (8) comparing the played-backportions of the recorded audio output of the components in view of theenvironmental conditions reflected in the played-back portions of therecorded video to provide a relative comparison of the quality of thecomponents.

The present invention provides an effective testing method that permitsgreater consistency and accuracy. The system permits output generatedfrom the same broadcast signals received at the same time and locationto be directly and repeatedly compared, thereby eliminating the inherentdeficiencies caused by comparing output generated by different signalsat different times and locations. The system especially permits theoutput recordings to be analyzed by a single rater, thereby eliminatingthe inconsistencies resulting from differences in the subjective ratingmethods of different raters. The recordings can also be analyzed underlab conditions, eliminating problems caused by background noiseencountered outside of the lab. Further, the video recording permitsenvironmental conditions to be taken into account in rating thecomponents during playback. By viewing the environmental conditionssimultaneously with the recorded audio, noise and other deficiencies inthe output resulting from environmental conditions can be properlyassessed.

In a preferred embodiment, the recording devices are connected to thespeaker output of the component being tested, such as an AM/FM receiver.This eliminates background noise as well as noise generated by thespeakers or by the electrical circuit feeding the speakers.

In another preferred embodiment, the recorded signals are analyzed usinga computer analysis system. The system permits the audio and videorecordings to be synchronized and then analyzed under laboratoryconditions. A single rater can thus test two separate systems producingsound from the same broadcast. The computer analysis system permits therecordings to be played in a variety of different modes that facilitatedirect comparison of the sound recordings from the two components. Forexample, the system can play the same time interval of sound from bothcomponents to permit a more accurate comparison. Further, by reviewingthe video recording simultaneously with the audio recording, the ratercan take environmental conditions into consideration when rating thecomponents.

The computer analysis system also provides the ability to plot therelative amplitude of the recorded audio over a range of frequencies.This permits the analyst to make a visual comparison of different audiorecordings. In a preferred embodiment, the system provides the abilityto plot two separate audio recordings simultaneously so that directcomparisons of the two audio recordings are possible.

In another aspect, the present invention provides a method forevaluating the quality of an audio recording. The method generallyinvolves analyzing the level of any signals present outside thefrequency range of normal sound. A particularly efficient embodiment ofthis method useful with FM broadcasts is to compute the differencebetween the relative amplitude of the FM pilot signal at 19 KHz with therelative amplitude of sound at 17 KHz. This method provides an objectiverating from which to objectively compare the quality of differentcomponents. By computing the difference between the pilot signal at 19KHz and the noise at 17 KHz, variations in the volume settings betweentwo components can be taken into account in the rating.

These and other objects, advantages, and features of the invention willbe readily understood and appreciated by reference to the detaileddescription of the preferred embodiment and the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flow chart showing the general steps of the qualitycomparison method of the present invention;

FIG. 2 is a flow chart showing the general steps of theplayback/analysis method of the present method;

FIG. 3 is a flow chart showing the general steps of the automatic ratingmethod of the present invention;

FIG. 4 is a screen image of the management software of the presentinvention;

FIG. 5 is a schematic diagram of the playback/analysis software layoutof the present invention;

FIG. 6 is a flow chart showing the general steps of the audio file mergemethod of the present invention;

FIG. 7 is a schematic diagram of the general hardware components of thepresent invention; and

FIG. 8 is a schematic diagram of the hardware layout of a test vehicle.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

I. Overview

The present invention is directed to a method for evaluating the qualityof components having broadcast reception capabilities, such asautomotive sound systems. For purposes of disclosure, the presentinvention will be described in connection with the testing of twodifferent reception systems for automotive sound systems. The presentinvention is, however, well-suited for use in testing a wide variety ofcomponents having signal reception capabilities, such as cellularphones, AM/FM receivers and the like.

The general steps of the testing method are shown in FIG. 1. The methodgenerally includes the steps of (a) installing 10 the reception systemsto be tested in separate vehicles, (b) simultaneously traveling 12through a test route with the vehicles in close proximity, (c) recording14 the audio output of the tuner (or receiver) while the vehicles travelthrough the test route, (d) recording 16 a video recording of thevehicles traveling through the test route, and (e) after the vehicleshave completed the test route, analyzing 18 the recorded audio outputsimultaneously with the recorded video to provide an evaluation of thequality of the tested reception systems.

In a second aspect, the present invention provides a method foranalyzing the recorded information. The general steps of this method areillustrated in FIG. 2. As shown, the method includes the steps of (a)capturing 20 the recorded audio and recorded video as audio and videofiles in a computer, (b) synchronizing 22 the captured audio and videofiles, (c) playing back 24 at least portions of the audio files andvideo file in concert and (d) comparing 26 the audio output of the audiofiles in view of the video recording to provide a relative rating of thetest components.

In a third aspect, the present invention provides a method forobjectively analyzing and comparing the quality of recorded audiooutput. As illustrated in FIG. 3, the method includes the steps of (a)computing 28 the average relative amplitude of an audio file at afrequency of 19 KHz, (b) computing 30 the average relative amplitude ofthe audio file at a second selected frequency above about 15 KHz andbelow about 19 KHz, (c) subtracting 32 the computed average relativeamplitude of sound at the second selected frequency from the computedaverage relative amplitude of sound at 19 KHz to provide an objectiverating, and (d) repeating 34 these steps for each audio file. Thecomputed objective ratings of the audio files can be compared 36 toprovide an objective indication of the relative quality of the testedcomponents.

II. Recording Methods and Apparatus

To provide the most meaningful comparison between two reception systems,the comparison should be made with the two systems receiving the samebroadcasts at the same time and in approximately the same location. Ifnot, variations in the type of signal being broadcast (e.g. music,audio, etc.), the frequency of modulation and environmental conditionscan significantly affect the comparison.

As outlined above, the method for recording test data generally includesthe steps of: (a) installing 10 the reception systems (e.g. fixed mastantenna and glass antenna) to be tested in separate vehicles, (b)simultaneously traveling 12 through a test route with the vehicles inclose proximity, (c) recording 14 the audio output of the receiver whilethe vehicles travel through the test route and (d) recording 16 a videorecording of the vehicles traveling through the test route. It issometimes desirable to compare the quality of components tested indifferent test runs. Direct comparisons between recordings made duringdifferent test runs are suspect because noise levels between differenttest runs will deviate significantly due to the factors discussed above,including variations in environmental conditions. To permit meaningfulcomparisons, the output from a reference system can be recorded duringeach test run, preferably by including a test vehicle fitted with thereference system in each test convoy. The reference vehicle permits therater or analyst to make comparisons between components of differenttest runs by comparing the relative quality of the test componentsagainst the corresponding reference components.

In order to collect audio output, the reference and test vehicles areequipped with an audio recording device, such as a digital audio tape(“DAT”) recorder. DAT recorders provide high quality sound recordingsand are therefore particularly well-suited for use in the presentinvention. DAT recorders are commercially available from a wide varietyof well-known suppliers. The DAT recorders preferably includeconventional analog input and digital output jacks to permit the DATrecorders to record analog output from the receiver and provide digitaloutput to the computer analysis system as described in more detailbelow. A DAT recorder is preferably connected to the speaker output ofthe receiver in each test vehicle.

In addition to the audio recording device, at least one of the vehiclesis equipped with a video recording device, such as a digital camcorder.The digital camcorder is preferably mounted to the dash within thevehicle that will travel last in the convoy, typically the referencevehicle. This permits the camcorder to record the preceding vehicleswhile simultaneously recording the test route, including theenvironmental conditions encountered along the route. The videorecording permits the rater to be aware of environmental conditions whenlater reviewing the audio recordings taken along the test route.Further, by video recording all of the test vehicles, the rater canconfirm that the vehicles remained in close proximity to one anotherthroughout the test route.

The test route is selected to pass through regions in which particulartest conditions (or defects in the signal) are likely to occur. Forexample, with respect to AM broadcasts, the test route may pass throughregions in which signal intrusion, signal overload, weak station fadeout and power line noise are likely to be encountered. With respect toFM broadcasts, the test route may be selected to pass through regionswhere signal overload, multipath fading, adjacent channel interference,medium strength signal and weak station fade out are likely to occur.These and other “test conditions” are well-known and can be addressed byselecting the appropriate test route. The creation and use of testroutes is also well-known, and will not be described in detail.

The present invention is described in connection with the testing of tworeception systems. Accordingly, two test vehicles are provided and eachis equipped with one of the two reception systems to be tested. To helpensure that any differences in the recorded audio output areattributable to the receptions systems, the vehicles are preferablyequipped with identical sound systems (e.g. receivers, speakers, etc.).DAT recorders are connected to the speaker output of the receiver foreach system. In addition, a reference vehicle is fitted with a referencesound system as well as a DAT recorder and a video recorder. The DATrecorder is connected to the speaker output of the reference receiver.The video recorder is mounted to the dash of the reference vehicle torecord video through the windshield of the test vehicle, therebyrecording the preceding test vehicles as well the environmentalconditions encountered during the test run.

Once the vehicles are properly fitted, the reference and test vehiclesare ready to collect test data. The test and reference vehicles are thendriven to the beginning of the test route. In the preferred embodiment,both AM and FM broadcasts will be recorded, thereby permitting lateranalysis of both AM and FM reception. The audio system for each of thevehicles is then set to the pre-determined frequency and band, such as94.5 FM. The audio and video recorders are then started and the vehiclesbegin to travel through the test route in convoy. Effort is made tomaintain the vehicles in close proximity so that they are subject toessentially the same environmental conditions throughout the test route.The reference vehicle is driven at the rear of the convoy with the videorecorder recording the environment and the test vehicles as they travelthrough the test route. If desired, the recorded broadcast frequency canvary between different legs of the test route. For example, the vehiclesmay approximately simultaneously switch from one station to another fordifferent portions of the test route. Once the vehicles have completedthe FM portion of the test route, the audio systems are switched to thedesired frequency in the AM band. The vehicles then convoy through theAM portion of the test route while again recording both audio and video.As with the FM band, the vehicles may approximately simultaneouslyswitch between different AM broadcast frequencies during the test. Theorder in which the AM and FM bands are tested is not material and mayvary from application to application.

III. Preparing the Test Data for Analysis

Once the test data (i.e. the audio recordings and video recording) iscollected, it is brought back to the lab for evaluation. In thepreferred embodiment, the test data is evaluated with the aid of acomputer analysis system. The computer analysis system includes audioand video capabilities which permit the analyst to capture andsynchronize the audio and video recordings. The analyst can then playback at least selected portions of the captured audio and videorecordings in concert to provide a relative comparison of the quality ofthe two tested reception systems. The analyst can also plot the relativeamplitude of the captured audio recordings, thereby permitting a visualcomparison of the captured audio recordings.

In general, the computer analysis system includes a high-performancepersonal computer 200 having a variety of audio and video accessories(See FIG. 7). To provide the processing power needed to performreal-time analysis, the computer preferably includes dual-500 MHzPentium processors (not shown) and 128M of RAM (not shown), as well ashigh speed SCSI interfaces for the hard drive and CD drive (not shown).To permit capture of the audio and video recordings, the computer 200preferably includes a conventional full duplex sound card 202, such as aSoundBlaster Live card available from Creative Labs, Inc., and aconventional video capture card 204, such as Matrox Marvel cardavailable from Matrox Graphics Inc. The SoundBlaster Live sound card (orother sound card) also provides high-quality audio output to an externalsound system 206. As described below, off-the-shelf audio and videosoftware as well as a customized piece of software are installed on thecomputer to manage the audio and video capture and playback processes.

The audio recordings from the test and reference vehicles are capturedby the computer using conventional techniques and apparatus. The audiofiles are preferably captured in the computer 200 using a conventionalsound card 202 and off-the-shelf audio software, such as WaveLabsoftware available from Steinberg. The digital output of the DATrecorders 206 a-c is preferably connected directly to the digital inputof the sound card 202 using conventional audio cables. If the DATrecorders 206 a-c do not provide digital output or the sound card 202does not accept digital input, the data can be loaded using conventionalanalog-to-digital or digital-to-analog circuitry. The various audiorecordings from the different DAT recorders 206 a-c are separatelycaptured and stored by the computer 200 in a conventional storage device(e.g. hard disk) as separate audio files. The audio files are preferablystored in a standard audio file format, such as “.wav” format.

The video file is captured by the computer 200 using a conventionalvideo capture card 204 and conventional video software, such as MatroxPowerDesk by Matrox Graphics Inc. The output of the video recorder 208is connected to the video card 204 using conventional cables andconnectors, such as an S-video connector. The video recording is thencaptured in a conventional manner and stored by the computer 200 in aconventional storage device (e.g. hard disk) as a video file in astandard video file format, such as “.avi” or “.mov” format.

Once the audio and video recordings have been captured and stored, theyare synchronized using one of a variety of methods. Synchronizing thefiles generally involves the process of cutting the files so that theystart at the same point in time and extend for the same length of time.One preferred method for synchronizing the audio files is to embedmarkers in the audio recordings during the test phase, for example, byplaying a signal or tone at the desired starting point that is recordedalong with the audio output. The markers can be used to quickly locatethe starting point of the files during the synchronization process. Themarkers can be embedded in the recordings in several ways. The preferredmethod is to provide each test vehicle with a marker generator 250 thatis triggered remotely by an FM signal. The FM signal is generated by acontrol transmitter 260 located in the reference vehicle or one of thetest vehicles. As shown schematically in FIG. 8, the marker generator250 is connected between the receiver 252 and the DAT recorder 206. Themarker generator 250 includes conventional FM receiving circuitry (notshown) operatively coupled with conventional signal generating circuitry(not shown) in a conventional manner. The marker generator 250 isdesigned to trigger the signal generating circuitry upon recognition ofthe start signal. The marker generators 250 in each vehicle are designedto be triggered by the same reference signal. Accordingly, the markergenerators 250 are simultaneously triggered upon transmission of thestart signal by a control transmitter 260. The control transmitter 260is a conventional FM transmitter having the ability to transmit the FMstart signal. More specifically, upon actuation, the control transmitter260 transmits an FM signal at a predetermined frequency, such as a 0.5second tone at 18 KHz, in a conventional manner. This signal isbroadcast with enough power reach each of the marker generators 250 inthe vehicles. Upon recognition of the FM signal generated by the controltransmitter 260, the marker generators 250 trigger the signal generatingcircuitry to create a pulse, spike or other distinctive marker that isembedded in the audio output being fed into the DAT recorder 206. Thismarker is recorded along with the audio output by the DAT recorder 206.If desired, each marker generator 250 can be configured to generate adifferent pulse, spike or marker in the audio recording, therebypermitting the audio recording to be quickly and easily associated witha particular marker generator 250 and consequently a particular testvehicle and test system. During preparation for analysis, the markerscan provide an audible and visual indication that can be used tosynchronize the various recordings. In the preferred embodiment, theaudio software is used to view a plot of the frequency and relativeamplitude of the audio files. By visually inspecting this plot, the usercan locate the marker and cut the audio file so that it beginsimmediately at (or after) the marker. Once the beginning is cut to thestarting point, the end of the audio file can be cut so that it extendsfor the desired length of time. The process is repeated until all of theaudio files have been cut to start at the same time with respect to themarker and run for the same amount of time thereafter. With this method,the video file is preferably synchronized by comparing the time/datestamp on the video recording with the time/date stamp on the DATrecorders 206. The video files can be synchronized by either capturing aportion of the video recording that encompasses the desired section andcutting it to start and stop at the same time as the synchronized audiofiles (based on the time/date stamps of the audio and video files) or byusing the time/date stamps to start and stop the video capture processat the same starting and stopping times as the synchronized audio files.

A second method for embedding a marker in the audio recordings is tobroadcast the marker over the FM frequency that is being played by theaudio systems. The marker is broadcast by a conventional FM transmitterwith enough power to reach each of the test vehicles. The marker willautomatically be recorded with the audio output and can later be used asa reference point for synchronizing the audio files.

Another method for synchronizing the audio and video files is tosynchronize them during the capture process. In this method, the captureprocess is started and stopped at the same times for each file. Thismethod is similar to one of the methods described above in connectionwith the synchronization of the video file, and relies on use of thetime/date stamp of the audio and video recorders. Accordingly, toutilize this method, it is important to synchronize the internal clocksfor the video recorder and each of the DAT recorders prior to therecording process. Once this is done, the video and DAT recorders can beset to automatically provide the recordings with synchronized time/datestamps. The recordings can then be captured as audio and video fileswith the capture process starting and stopping at the same times foreach recorder based on the time/date stamp provided with the recordings.

Yet another method for synchronizing the files is to use a remotecontrol for starting and stopping the video recorder and the DATrecorders. With this method, the remote control is capable oftransmitting start and stop signals that are recognized by the videorecorder and each of the DAT recorders. Accordingly, all of therecorders will start and stop recording simultaneously and the resultingrecordings will be automatically synchronized. The remote controlpreferably operates using conventional wireless technology, such as UHFor FM signals that are capable of reaching the video and DAT recordersin all of the vehicles at any point during the test route. For thismethod to function, the video recorder and the DAT recorders must becapable of receiving and responding to the control signals.

IV Playback and Analyzing the Test Data

Once the audio files have been captured and synchronized, they are readyfor playback and analysis. Playback is provided using primarilyoff-the-shelf audio and video software that is preferably controlled bycustomized management software. The management software facilitatescomparison and analysis of the audio and video files by coordinatingoperation of the audio and video software and providing a variety ofuseful playback modes. In the described embodiment, Windows Media Player(standard with Windows) is used to play the audio and video files, andSpectraLab software available from Sound Technology, Inc. is used toplot the relative amplitude of the audio files. The SpectraLab softwarehas the ability to analyze and separately plot in real-time the relativeamplitude of the left and right stereo channels of an audio signal overa range of frequencies, such as 0.0 KHz to 20.0 KHz. The SpectraLabplots are generally conventional and they show time along the horizontalaxis, frequency along the vertical axis and relative amplitude based oncolor/intensity of the plotted point. Windows Media Player andSpectraLab are capable of interacting with other software, such as themanagement software, using conventional calling techniques. For example,Windows Media Player is capable of playing both audio or video files atthe direction of other software. The Windows Media Player can even bedirected to start playback at a specified time in the file. Similarly,SpectraLab has the ability to start and stop real-time analysis of audioinput at the direction of other software. SpectraLab also has theability to return the results of its analysis to the calling software.Methods for controlling these and other audio and video softwarepackages are well-known to those skilled in the art and will not bedescribed in detail. It should also be noted that Windows Media Playerand SpectraLab are merely exemplary and may be replaced by otherconventional audio and video software.

In general, the management software is used to select the appropriateaudio and video files and to control the playing and plotting of thesefiles by SpectraLab and Windows Media Player. The management software isrelatively simple in operation and design, and is easily implemented inany of a variety of programming languages by one skilled in the art. Inthe preferred embodiment, the management software is written in VisualBasic, and provides a variety of modes for listening to the audio filesand playing the video files. The user or analyst preferably controls themanagement software using a generally conventional GUI interface thatpermits the analyst to select and move between various modes ofoperation. The overall function of the management software will bedescribed in connection with FIGS. 4 and 5. FIG. 4 is a screen imageshowing the main screen 100 of the management software. As shown, thescreen includes a video window 102 for displaying the video file duringplayback, an audio window 104 for displaying a plot of the relativeamplitude of the left and right stereo channels of an audio file, a fileidentification area 106 for identifying the various audio files loadedinto the system, and an information area 108 for presenting informationdescribing or identifying the test. The screen image illustrated in FIG.4 is merely exemplary and will vary from application to application withthe design and construction of the GUI interface. The screen layout andavailable control options will vary from application to application. Thegeneral software layout is illustrated in FIG. 5. As shown, themanagement software 210 opens Video Player 212, two instances of AudioPlayer 214, 216 and SpectraLab 218.

Upon start-up, the management software opens an instance of WindowsMedia Video Player (“Video Player”) to create video window 102 and aninstance of SpectraLab to create audio window 104 (See FIG. 5). As shownin FIG. 4, these two windows 102, 104 are integrated into the mainscreen 100 and are part of the GUI interface of the management software.The management software also open two instances of Windows Media AudioPlayer (“Audio Player”). These two Audio Players remain hidden andpermit up to two audio files to be played simultaneously as directed bythe management software. During playback, the Audio Players will provideoutput to the sound card. The output of the sound card is connected tothe sound system to provide audio output. In addition, the sound cardoutput is connected back to the sound card input, for example, byconventional audio cables extending between the audio output and inputjacks. The audio output is fed back into the sound card to permit theaudio signals to be fed to and analyzed in real-time by the SpectraLabsoftware. This functionality is permitted by the use of a full duplexsound card.

In operation, the analyst must first identify the audio and video filesto be analyzed. In the preferred embodiment, the audio and video filesalong with any textual description to be displayed by the managementsoftware are stored in an “.ini” file. The “.ini” file is a text filelisting the specific audio and video files and any desired textualinformation. For example, the “.ini” file will list the file name andlocation for all audio files recorded during a particular test as wellas the file name and location of the corresponding video file. Further,the “ini” file may include information identifying each of the files, aswell as information about the test, the systems tested and any desiredtest conditions. This information may be displayed by the managementsoftware as desired. The “.ini” file is typically created after thefiles have been synchronized. Instead of the “.ini” file, the audio andvideo files as well as any desired textual information can be input bythe analyst directly into the management software. However, the “.ini”file is preferable in most applications because once it is built, theinformation need not be entered again and the user can load the entirecollection of files and related information by simply selecting theappropriate “.ini” file from within the management software. The “.ini”can be created in advance by a specialist so that the analyst is notrequired to enter any of the information.

Once specified by the analyst, the management software reads the “.ini”file and opens the audio and video files identified therein. Inaddition, the management software may integrate any informationcontained in the “.ini” file into the GUI interface.

After the files have been opened, the management software permits theaudio and video files to be played back in a variety of different modesof operation. In perhaps the most basic mode of operation, themanagement software permits the analyst to listen to and plot a singleaudio file while simultaneously viewing the corresponding video file.The management software sends a command to a single Audio Playerdirecting that Audio Player to play a specified audio file so that theaudio is output to the sound card and in turn to the sound system. Thesound card output is also fed back into the sound card input so that itcan be analyzed and plotted in real-time by the SpectraLab software. Themanagement software also sends a command to the Windows Viewer directingthat Viewer to play the corresponding synchronized video at the sametime as the audio files are being played. This permits the analyst toview the environmental conditions occurring when the audio recordingswere made. Accordingly, the analyst can discount or otherwise take intoconsideration noise caused by environmental conditions, such as badweather, travel under an overpass, movement adjacent a power line andthe like. Further, the management software sends a command to SpectraLabdirecting SpectraLab to provide real-time analysis and plot the audiosignal entering the sound card. Start and stop commands are sent toSpectraLab whenever the Audio Player is started or stopped.

The management software also preferably permits the analyst to start theplayback at any particular time in the audio and video files. Forexample, the analyst may want to playback a file beginning 30 secondsinto the recording. To provide this option, the management softwaresends a command to Audio Player directing it to play the appropriateaudio file beginning at the specified time in the file. Also, themanagement software directs the Video Player to play the correspondingvideo, also file beginning at the specified time in the file. IfSpectraLab analysis is also desired, the management software directs theSpectraLab software to start and stop real-time analysis as the AudioPlayer is directed to start and stop.

To facilitate comparison of different audio files, the managementsoftware permits the analyst to switch back and forth between thevarious audio files. For example, the management software preferablyincludes an “A/B” mode of operation in which the analyst can rapidlyswitch back and forth between two separate audio files. In this mode ofoperation, the analyst pre-selects to two files and once playback hasstarted, indicates when to switch between the two files. In this mode ofoperation, the management software utilizes a single Audio Player. Themanagement software sends a command to the Audio Player directing it toplay the first audio file and a command to the Video Player directing itto play the corresponding video file. When the analyst inputs thecommand to switch audio files, the management software sends a commanddirecting the Video Player and the Audio Player to stop. The managementsoftware also queries the Audio Player to determine the time in the fileat which play stopped. The management software then sends a command tothe Audio Player directing it to play the second audio file beginning atthe time in the file at which the first audio file stopped. It alsosends a command to the Video Player directing it to again play the videofile, also beginning at the time in the file at which the first audiofile stopped. The process of switching files is so rapid that thetransition is made without any perceptible delay. The process can berepeated and reversed to switch back and forth between the two files asdesired. If desired, additional audio files can be incorporated into theprocess, for example, permitting the user to cycle between three or moreaudio files. If SpectraLab analysis and plotting is desired, themanagement software directs the SpectraLab software to start and stopreal-time analysis as the Audio Player is directed to start and stop.

In another mode of operation, the management software utilizes twoWindows Audio Players to merge the left or right channel of one audiofile with the opposite channel of a second audio into a single stereosignal. When this merged signal is received by the SpectraLab software,the left and right channel plots will actually show and permitcomparison of the two different audio files. In operation, themanagement software generates the merged audio signal by: (a) opening150 two instances of Audio Player (if not already open), (b) adjusting152 the balance of the first Audio Player 214 to full left of fullright, (c) adjusting 154 the balance of the second Audio Player 216 tofull left or full right, opposite the first Audio Player 214, (d)playing 156 the first audio file with the fist Audio Player 214, (e)simultaneously playing 158 the second audio file with second AudioPlayer 216, and (f) merging 160 the output of the first and second AudioPlayers 214, 216 into a single output signal. More specifically, themanagement software sends commands to two Audio Players directing eachto play one of the two audio files to be merged (See FIG. 6). Themanagement software also sends a command to the first Audio Playeradjusting its balance so that only the right channel is played and acommand to the second Audio Player adjusting its balance so that onlythe left channel is played, or vice versa. Windows automatically mergesthe output of the two Audio Players when they are played simultaneouslywithout any intervention or direction from the management software.Accordingly, when the two Audio Players are playing, a single mergedoutput signal is sent to the sound card with the output of one AudioPlayer in one stereo channel and the output of the other Audio Player inthe other stereo channel.

The GUI interface of the management software permits the analyst toeasily select the desired channels of the desired files, for example,through the use of input buttons that can be selected with an inputdevice such as a mouse. When the audio files are played, the mergedaudio output is played over the sound system allowing the analyst tocompare their respective signals by comparing the output of the left andright speakers. Further, the management software can start and stopSpectraLab as desired to plot the merged audio file. Because SpectraLabseparates and individually plots the left and right stereo channels ofthe audio input, it automatically separates and plots the two audiofiles. This permits the analyst to visual compare the two channels ofthe two audio files in real-time, seeing and comparing noise as itoccurs in the two merged audio files. In addition, in this mode ofoperation, the management software directs the Video Player to play thevideo file at the same time as the Audio Player is directed to play themerged audio file. As a result, the Video Player plays the video filesynchronized with the audio files. Playback of the merged audio filesand video files can be started and stopped at the desired times in thefiles as discussed above.

In yet another mode of operation, the management software permits theanalyst to repeatedly playback a selected portion or loop of the audioand video files. This capability can be used with merged audio from twoseparate audio files or with full audio from a single audio file. Themanagement software receives. input from the analyst indicating thestarting time and ending time of the playback loop. The managementsoftware then sends a command to the Audio Player (or two Audio Playersin merged operation) directing it to play the audio file beginning atthe specified loop starting time. A second command is sent to the VideoPlayer directing it to play the video file beginning at the specifiedloop starting time. Once playback has started, the management softwarerepeatedly queries the Audio Player, for example, every 0.5 seconds, todetermine the time the Audio Player is within the audio file. Each timea value is returned by the Audio Player, the management softwarecompares it with the specified loop ending time. When the managementsoftware determines that the Audio Player has reached the loop endingtime, the management software sends stop commands to the Audio Playerand Video Player. The management software then sends commands to theAudio Player and Video Player directing them to start playing the audioand video files at the specified loop starting time. The process repeatsas desired. The SpectraLab software can be used to analyze and plot thelooped audio output by sending appropriate start and stop commands toSpectraLab when the Audio Player is started and stopped.

In a further mode of operation, the “A/B” and “Loop” modes of operationare combined to permit the analyst to repeatedly listen to a selectedportion of the audio files, while selectively switching between thevarious audio files as desired.

In use, the analyst will select the desired playback mode. One skilledin the art will readily appreciate that the playback modes describedherein are merely exemplary and that a wide variety of additionalplayback modes are possible. For example, additional modes of operationare available by combining the various modes of operation discussedabove. The analyst is then able to compare and contrast the audio outputfrom the various audio files to provide a quality comparison of thedifferent tested systems. For example, the analyst can compare andcontrast the presence and extent of noise, interference, fade out orother conditions in the various audio files. These conditions arereadily discernable by those skilled in the art. To aid this comparison,the analyst can compare and contrast the relative amplitude plotsprovided by SpectraLab. As noted above, the plots permit the analyst toessentially “see” noise as well as to compare the signal level ofvarious audio files. Further, by viewing the video file whilesimultaneously listening to the audio files, the analyst is able toconsider and account for environmental conditions that may have impactedthe quality of sound produced by the tested systems.

V. Automatic Rating Process

In an effort to further reduce the subjectivity of the analysis process,the management software also provides the ability to automatically ratethe quality of an audio file, or a portion of an audio file, of arecorded FM broadcast. In general, the automatic rating process involvesan analysis of noise present at frequencies above the normal modulatingfrequency of the recorded broadcast signal. With the exception of apilot signal broadcast at 19 KHz, desired sound in FM signals istypically modulated at or below 15 KHz. Because of this, any signalpresent above 15 KHz and below 19 KHz can, for purposes of rating, bepresumed to be noise. Accordingly, an indication of the amount of noisein a particular recorded signal can be determined by summing, averagingor otherwise considering the relative amplitude of any signals presentin that range. This process of computing the relative amplitude ofsignal over this entire range for even small portions of an audio filewould require immense amounts of computer processing. Because of this,the present invention preferably uses a shorthand method for analyzingthe noise present above 15 KHz. The shorthand method is to consider thelevel of the signal at only a single frequency in the 15 KHz to 19 KHzrange, such as 17 KHz, rather than the entire range. This method hasproven to provide an effective and meaningful rating. Because the levelof a signal at any given frequency will vary with the volume setting ofthe system as it is being recorded, a straight comparison betweendifferent systems would only be meaningful if the different systems wereset to the same volume during the recording process. To account for thisproblem without requiring the recorded systems to be set to the samevolume setting, the present invention considers the relative amplitudeof the pilot signal broadcast at 19 KHz when computing the automaticrating. This is possible because the level of the pilot signal, like thelevel of noise, increases and decreases with the volume setting of thetest system. Therefore, in the preferred embodiment, the automaticrating system rates a recorded FM broadcast by comparing the signallevel at 19 KHz with the signal level at 17 KHz. More particularly, themanagement software computes a relative rating by subtracting theaverage relative amplitude of the signal at 17 KHz from the averagerelative amplitude of the signal at 19 KHz. This process is facilitatedby SpectraLab, which has the ability to compute in real-time the averagerelative amplitude of an audio signal over a range of frequencies or atany given frequency. Accordingly, to automatically rate a particularaudio file, the management software sends a command to the Audio Playerdirecting it to play the portion of a file to be rated and also sends acommand to SpectraLab directing it to separately compute, in real-time,the average amplitude of the input signal at 17 KHz and the averageamplitude of the signal at 19 KHz. When the audio file or the portion ofthe audio file to be rated is complete, the management software sendscommands to the Audio Player and SpectraLab directing them to stop. Themanagement software also queries SpectraLab to return the computedaverage values at 17 KHz and 19 KHz. When the values are returned, themanagement software subtracts the computed average amplitude at 17 KHzfrom the computed average amplitude at 19 KHz to provide a relativerating. The identical portion of the next audio file can then beprocessed in an identical manner to provide a relative rating for thataudio file. The process can be repeated for any additional audio files.The relative ratings for each audio file can be compared to provide ameaningful representation of the amount of noise present in theautomatically rated files, in turn providing a relative rating of therelative quality of the tested components.

The above description is that of a preferred embodiment of theinvention. Various alterations and changes can be made without departingfrom the spirit and broader aspects of the invention as defined in theappended claims, which are to be interpreted in accordance with theprinciples of patent law including the doctrine of equivalents. Anyreference to claim elements in the singular, for example, using thearticles “a”,“an”,“the” or “said”, is not to be construed as limitingthe element to the singular.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:
 1. A method for testingvehicle components with signal reception capabilities, comprising thesteps of: providing a first vehicle with a first component and a firstrecording means for recording signals from the first component;providing a second vehicle with a second component and a secondrecording means for recording signals from the second component;providing at least one of the first and second vehicles with a videorecording device; traveling through a test route with both the firstvehicle and the second vehicle in close proximity to one another;simultaneously recording a first audio recording of output from thefirst component with the first recording means and a second audiorecording of output from the second component with the second recordingmeans during at least a portion of said traveling step; recording avideo recording during the portion of said traveling step simultaneouslywith said simultaneous recording step; and comparing the first audiorecording, second audio recording and video recording to obtain arelative quality evaluation of the first component and the secondcomponent.
 2. The method of claim 1 further comprising the steps of:capturing the audio recording of the first component in a computer as afirst audio file; and capturing the audio recording of the secondcomponent in the computer as a second audio file.
 3. The method of claim2 further comprising the step of capturing the video recording in thecomputer as a video file.
 4. The method of claim 3 wherein saidcomparing step includes the steps of: playing back with a computer atleast portions of the first audio file and the second audio file; andplaying back with a computer at least portions of the video file, thevideo file playback being synchronized with the audio file playbackwhereby environmental conditions encountered while recording the firstaudio recording and the second audio recording can be viewedsimultaneously with the playback audio file playback of the audiorecordings created under those environmental conditions.
 5. The methodof claim 4 further comprising the step of synchronizing the first audiofile with the second audio file.
 6. The method of claim 5 furthercomprising the step of synchronizing the video file with the first andsecond audio files.
 7. The method of claim 6 wherein said step ofsynchronizing the first and second audio files includes the step ofcutting at least one of the first and second audio files in a computerso that the first and second audio files begin and end at substantiallythe same points in time.
 8. The method of claim 7 wherein said step ofsynchronizing includes the step of embedding a marker in the first andsecond audio files during said simultaneous recording step.
 9. Themethod of claim 8 wherein said step of synchronizing the video file withthe first and second audio files includes the step of cutting the videofile in a computer so that it begins and ends at substantially the samepoints in time as the first and second audio files.
 10. The method ofclaim 9 wherein said comparing step includes the step of computing anddisplaying in a computer data indicative of the signal level at variousfrequencies of at least portions of the first audio file and the secondaudio file, the computing and displaying step occurring inreal-timereal-time during playback of the first audio file and thesecond audio file.
 11. The method of claim 10 wherein the dataindicative of the signal level at various frequencies is further definedas relative amplitude.
 12. The method of claim 11 wherein said computingand displaying step is further defined as: merging in a computer a firststereo channel of the first audio file with a second stereo channel ofthe second audio file to generate a merged audio output; computing anddisplaying in a computer a relative amplitude of at least portions ofthe first audio file contained in the first stereo channel of the mergedaudio output; and computing and displaying in a computer a relativeamplitude of at least portions of the second audio file contained in thesecond stereo channel of the merged audio output, both of said computingand displaying steps occurring in real-time during playback of the firstaudio file and the second audio file.
 13. A method for recording andplaying back data for comparing vehicle components with signal receptioncapabilities, comprising the steps of: recording audio output from afirst component while traveling a test route, the first componentgenerating output from a broadcast signal at a frequency; recordingaudio output from a second component simultaneously with said firstaudio recording step while traveling the test route, the secondcomponent generating output from the broadcast signal at the frequency;recording video of environmental conditions encountered while travelingthe test route simultaneously with said first and second audio recordingsteps; playing back at least selected portions of the recorded audiooutput from the first component and the recorded audio output from thesecond component; and playing back at least selected portions of therecorded video corresponding to the played-back portions of the recordedaudio output from the first component and the recorded audio output fromthe second component, the playing back of the recorded video occurringsimultaneously with and in synchronized relationship to thecorresponding portions of the played-back portions of the recorded audiooutput from the first component and the recorded audio output from thesecond component.
 14. The method of claim 13 further comprising thesteps of: capturing the recorded audio output from the first componentin a computer as a first audio file; capturing the recorded audio outputof the second component in the computer as a second audio file; andwherein said audio playback step is further defined as playing back, inthe computer, at least selected portions of the first audio file and thesecond audio file.
 15. The method of claim 14 further comprising thestep of capturing the recorded video in the computer as a video file,said video playback step being performed in the computer.
 16. The methodof claim 15 further comprising the step of computing and displaying in acomputer data indicative of the signal level at various frequencies ofat least portions of the first audio file and the second audio file, thecomputing and displaying step occurring in realtime during said audioplayback of the first audio file and the second audio file.
 17. Themethod of claim 16 further comprising the step of synchronizing thefirst audio file with the second audio file.
 18. The method of claim 17further comprising the step of synchronizing the video file with thefirst and second audio files.
 19. The method of claim 18 wherein saidthe step of synchronizing the first and second audio files includes thestep of cutting at least one of the first and second audio files in acomputer so that the first and second audio files begin at the samepoint in time during the simultaneous recording step.
 20. The method ofclaim 19 wherein said the step of synchronizing the first and secondaudio files includes the step of cutting at least one of the first andsecond audio files in a computer so that the first and second audiofiles end at the same point in time during the simultaneous recordingstep.
 21. The method of claim 20 wherein said the step of synchronizingthe video file with the first and second audio files includes the stepof cutting the video file in a computer so that it begins and ends atthe same point in time during the recording step as the first and secondaudio files.
 22. The method of claim 21 wherein the data indicative ofthe signal level at various frequencies is further defined as relativeamplitude.
 23. The method of claim 22 wherein said computing anddisplaying step includes computing and displaying relative amplitude ofat least selected portions of the first audio file simultaneously withcorresponding portions of the second audio file.
 24. The method of claim22 wherein said computing and displaying step is further defined as:merging in a computer a first stereo channel of the first audio filewith a second stereo channel of the second audio file to generate amerged audio output; computing and displaying in a computer a relativeamplitude of at least portions of the first audio file contained in thefirst stereo channel of the merged audio output; and computing anddisplaying in a computer a relative amplitude of at least portions ofthe second audio file contained in the second stereo channel of themerged audio output, both of said computing and displaying stepsoccurring in real-time during playback of the first audio file and thesecond audio file.
 25. A method for comparing the quality of receptionsystem, comprising the steps of: providing a first vehicle with an audiosystem and a first reception system to be tested; providing a secondvehicle with an audio system and a second reception system to be tested;traveling through a test route with the first vehicle and the secondvehicle in close proximity to one another; simultaneously recordingoutput from the first audio system and the second audio system duringsaid traveling step with the first and second audio systems producingoutput from a predetermined frequency; recording video of environmentalconditions encountered by the first and second vehicles during saidtraveling step; playing back at least selected portions of the recordedaudio output from the first audio system and the recorded audio outputfrom the second audio system; playing back at least selected portions ofthe recorded video corresponding to the played-back portions of therecorded audio output, the playing back of the recorded video occurringsimultaneously with and in synchronized relationship to thecorresponding portions of the played-back portions of the recorded audiooutput; and comparing the recorded output from the. first audio systemwith the recorded output from the second audio system in view of therecorded video to obtain a relative quality evaluation of the firstreception system and the second reception system.
 26. The method ofclaim 25 wherein the audio system of the second vehicle is substantiallyidentical to the audio system of the first vehicle, whereby differencesnoted during said comparing step are attributable to differences betweenthe first and second reception systems.
 27. A method for testing vehiclecomponents with signal reception capabilities, comprising the steps of:recording audio output from a first component while traveling a firsttest route, the first component generating output from a first broadcastsignal; recording audio output from a reference component simultaneouslywith said first audio recording step while traveling the first testroute, the reference component generating output from the firstbroadcast signal; recording audio output from a third component whiletraveling a second test route, the first component generating outputfrom a second broadcast signal; recording audio output from thereference component simultaneously with said third audio recording stepwhile traveling the second test route, the reference componentgenerating output from the second broadcast signal; playing back atleast selected portions of the recorded audio output from the firstcomponent and the simultaneously recorded audio output from thereference component; playing back at least selected portions of therecorded audio output from the third component and the simultaneouslyrecorded audio output from the reference component; and comparing arelative quality of the first audio recording and the simultaneouslyrecorded audio output from the reference component with a relativequality of the third audio recording and the simultaneously recordedaudio output from the reference component to obtain a relative qualityevaluation of the first component and the third component.
 28. Themethod of claim 27 further comprising the steps of: recording video ofenvironmental conditions encountered while traveling the first testroute simultaneously with said first and second audio recording steps;recording video of environmental conditions encountered while travelingthe second test route simultaneously with said third and fourth audiorecording steps; wherein said playback step further includes playingback at least selected portions of the recorded video corresponding tothe played-back portions of the recorded audio output from the firstcomponent and the recorded audio output from the third component, theplaying back of the recorded video occurring simultaneously with and insynchronized relationship to the corresponding portions of theplayed-back portions of the recorded audio output from the firstcomponent and the recorded audio output from the third component; andsaid comparing step includes considering the played-back portions of therecorded video when comparing the first audio recording and thesimultaneously recorded audio output from the reference component andwhen comparing the third audio recording and the simultaneously recordedaudio output from the reference component.